The successful operation of Shanghai-Hong Kong Stock Connect Trading Mechanism has broadened the investment channels of investors, promoted the convergence of domestic capital market and international capital market， and had great influence upon China’s A-share stock market stability． Based on the complex network theory， the MST-Kruskal algorithm is used to construct different networks composed of the Shanghai Stock Connect market， the Hong Kong Stock Connect market or the Shanghai-Hong Kong stock market， and the anti-attack performances of different networks， in four stages before and after the pilot project and the official operation of Shanghai-Hong Kong Stock Connect， are simulated． Then the stability of China stock market is studied． Our results show that， with the implementation of Shanghai-Hong Kong Stock Connect program， the market networks of Shanghai Stock Connect and Hong Kong Stock Connect merge constantly while maintaining their local cluster． Shanghai Stock Connect market network has a strong aggregation， while Hong Kong Stock Connect market network is relatively decentralized． Besides， the two markets maintain good robustness when facing random attacks， and show a certain vulnerability under a hostile attack． After Shanghai-Hong Kong Stock Connect launched officially， the combination of the two markets improves the stability of stock markets．In all， our conclusions provide a new logic for the stability research of Chinese stock market， and new enlightenment for regulators to develop regulatory policies and listed companies to maintain the stability of their stock prices．